In any construction procedure, especially in residential construction, almost any squeak may be undesirable. This is especially true in a load bearing surface, especially a surface subject to foot traffic such as floor or a stair.
A squeaky area in a structure subject to foot traffic is an indication of poor quality in that structure. In fact, it is quite possible to say that a floor squeak or a stair squeak is completely undesirable. Whether that indication of poor quality is accurate or merely perceived, it is highly desirable to eliminate the squeaky area accurately and efficiently.
A squeaky floor is highly undesirable. The same logic applies to a squeaky stair, because a squeaky stair is also highly undesirable. Yet, it is extremely difficult to provide a squeak-proof floor or a squeak-proof stair. Even if extra care is taken during construction to avoid such an occurence, shrinking or expanding of wood can still cause the squeak.
As the floor and subfloor (if necessary) are installed in a house and attached to the joists that support the floor or the stair tread is attached to the staircase, tight fittings can be made to avoid squeaks. However, over a period of time, the wood shrinks or expands thereby changing the structure of the original joint. A nail used may also become loose.
Any one or a combination of these changes can create a space. This space between the floor, the subfloor and the joist can cause a squeak when pressure is applied to the area around the space. In a similar fashion, the squeak can occur on a stair.
Once the squeaks occur, it is extremely difficult to eliminate the squeaks from the structure. A major effort is required to remove whatever decoration has been placed over the floor or the stair, to repair or to eliminate the squeaky area, and to restore the floor or the stair to its original appearance. There is a major reconstruction problem to remove the squeaky area and replace it with materials which will not squeak.
Furthermore, there is no perfect way to insure that the squeak is actually repaired at the time the repairs are finished. It is almost always necessary to restore the decoration and test for the squeak by the trial and error method. It thus becomes highly desirable to avoid this problem and simplify the elimination of the squeaks.